Relaying techniques, in which a source node communicates to a destination node with the help of a relay, have been proposed as a cost-effective solution to address the increasing demand for high data rates and reliable services over the air. As such, it is crucial to design relay systems that are able to not only provide high Spectral efficiency, but also fully exploit the diversity of the relay channel.
標(biāo)簽： Amplify-and-Forward Relaying
上傳時(shí)間： 2020-05-26
上傳用戶：shancjb
The growing interest for high data rate wireless communications over the last few decades gave rise to the emergence of a number of wideband wireless systems. The resulting scarcity of frequency spectrum has been forcing wireless system designers to develop methods that will push the Spectral efficiency to its limit.
標(biāo)簽： Algorithms Baseband Receiver
上傳時(shí)間： 2020-05-26
上傳用戶：shancjb
Cognitive radio has emerged as a promising technology for maximizing the utiliza- tion of the limited radio bandwidth while accommodating the increasing amount of services and applications in wireless networks. A cognitive radio (CR) transceiver is able to adapt to the dynamic radio environment and the network parameters to maximize the utilization of the limited radio resources while providing flexibility in wireless access. The key features of a CR transceiver are awareness of the radio envi- ronment (in terms of spectrum usage, power Spectral density of transmitted/received signals, wireless protocol signaling) and intelligence.
標(biāo)簽： Cognitive Wireless Network
上傳時(shí)間： 2020-05-26
上傳用戶：shancjb
The recent developments in full duplex (FD) commu- nication promise doubling the capacity of cellular networks using self interference cancellation (SIC) techniques. FD small cells with device-to-device (D2D) communication links could achieve the expected capacity of the future cellular networks (5G). In this work, we consider joint scheduling and dynamic power algorithm (DPA) for a single cell FD small cell network with D2D links (D2DLs). We formulate the optimal user selection and power control as a non-linear programming (NLP) optimization problem to get the optimal user scheduling and transmission power in a given TTI. Our numerical results show that using DPA gives better overall throughput performance than full power transmission algorithm (FPA). Also, simultaneous transmissions (combination of uplink (UL), downlink (DL), and D2D occur 80% of the time thereby increasing the Spectral efficiency and network capacity
標(biāo)簽： Full-Duplex Cells Small
上傳時(shí)間： 2020-05-27
上傳用戶：shancjb
To meet the future demand for huge traffic volume of wireless data service, the research on the fifth generation (5G) mobile communication systems has been undertaken in recent years. It is expected that the Spectral and energy efficiencies in 5G mobile communication systems should be ten-fold higher than the ones in the fourth generation (4G) mobile communication systems. Therefore, it is important to further exploit the potential of spatial multiplexing of multiple antennas. In the last twenty years, multiple-input multiple-output (MIMO) antenna techniques have been considered as the key techniques to increase the capacity of wireless communication systems. When a large-scale antenna array (which is also called massive MIMO) is equipped in a base-station, or a large number of distributed antennas (which is also called large-scale distributed MIMO) are deployed, the Spectral and energy efficiencies can be further improved by using spatial domain multiple access. This paper provides an overview of massive MIMO and large-scale distributed MIMO systems, including Spectral efficiency analysis, channel state information (CSI) acquisition, wireless transmission technology, and resource allocation.
標(biāo)簽： Large-scale Antenna Systems
上傳時(shí)間： 2020-05-27
上傳用戶：shancjb
In order to improve the Spectral efficiency in wireless communications, multiple antennas are employed at both transmitter and receiver sides, where the resulting system is referred to as the multiple-input multiple-output (MIMO) system. In MIMO systems, it is usually requiredto detect signals jointly as multiple signals are transmitted through multiple signal paths between the transmitter and the receiver. This joint detection becomes the MIMO detection.
標(biāo)簽： Complexity Detection MIMO Low
上傳時(shí)間： 2020-05-27
上傳用戶：shancjb
The investigation of the propagation channel is becoming more and more important in mod- ern wireless communication. The demand for Spectral efficiency motivates exploitation of all channels that can possibly be used for communications. Nowadays, a common trend for designing physical layer algorithms is to adapt the transceiving strategy, either by maximizing the diversity gains or by utilizing the coherence of the channels to improve the signal-to-noise power ratio.
標(biāo)簽： Characterization Propagation Channel
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power Spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
標(biāo)簽： Telecommunications Processing Signal for
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
The explosion in demand for wireless services experienced over the past 20 years has put significant pressure on system designers to increase the capacity of the systems being deployed. While the Spectral resource is very scarce and practically exhausted, the biggest possibilities are predicted to be in the areas of Spectral reuse by unlicensed users or in exploiting the spatial dimension of the wireless channels. The former approach is now under intense development and is known as the cogni- tive radio approach (Haykin 2005).
標(biāo)簽： Multi-Antenna Wireless Channels Modeling
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
移動(dòng)通信網(wǎng)絡(luò)由于帶寬和技術(shù)的限制，遠(yuǎn)遠(yuǎn)不能滿足人們不斷高漲的無線上網(wǎng)需求。Wi-Fi作為無線接入技術(shù)MLAN的主流標(biāo)準(zhǔn)口益成熟，它能夠隨時(shí)隨地高速連接到Internet，極大地滿足了用戶對(duì)無線上網(wǎng)需求，受到消費(fèi)者的青睞。因而越來越多的移動(dòng)終端都集成了Wi-Fi功能，Wi-Fi和藍(lán)牙樣成為移動(dòng)終端的標(biāo)配。隨之而來的是wi-Fi和藍(lán)牙都工作在2.4CHZz ISM頻段而引發(fā)的互相 擾問題，導(dǎo)致數(shù)據(jù)吞吐量下降，語(yǔ)音質(zhì)量惡化失真，極端狀況下甚至導(dǎo)致鏈路斷開而不能正常工作。因此，必須尋求有效的措施和方法，實(shí)現(xiàn)兩種技術(shù)在近距離的和諧共存，這已成為非常迫切的技術(shù)需要，也成為人們研究的一個(gè)熱點(diǎn)和難點(diǎn)。近距離WiFi和藍(lán)牙互相1擾的問題，目前已經(jīng)形成了非常多的有效解決機(jī)制，包括基于Wi-Fi的PTA（Packet Traffic Arbitration）、AWMA（Alternating Wireless Medium Access）和DSE（Deterministic Spectral Excision），其中PTA和AWMA機(jī)制在Wi-Fi側(cè)MAC層實(shí)現(xiàn)，通過協(xié)調(diào)Wi-Fi和藍(lán)牙的幀發(fā)射時(shí)間來避免相互干擾：而DSE是在Wi-Fi側(cè)物理層PHY實(shí)現(xiàn)，通過一個(gè)可編程帶阻濾波器（Notch Filter）來阻止來白藍(lán)牙的窄帶干擾。還有基于藍(lán)牙側(cè)的AFH（Adaptive Frequency Hopping），它通過跳頻，自動(dòng)避開被干擾的頻點(diǎn)，從而大大提高了藍(lán)牙傳輸性能。
上傳時(shí)間： 2022-06-20
上傳用戶：zhanglei193
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